Darren A. Miller

Use of Forest Edges by Bats in a Managed Pine Forest Landscape

Abstract Forest edges often have increased species richness and abundance (edge effect) and affect spatial behaviors of species and dynamics of species interactions. Landscapes of intensively managed pine (Pinus spp.) stands are characterized by a mosaic of patches and linear forest edges. Managed pine forests are a primary landscape feature of the southeastern United States, but the effects of intensive management on bat communities are poorly understood. Insectivorous bats are important top predators in nocturnal forest food webs. We examined bat foraging behavior along forest edges and in 4 structurally distinct stand types (open-canopy pine, prethinned pine, thinned pine, and unmanaged forest) within a managed pine forest in the coastal plain of North Carolina, USA. During May–August, 2006 and 2007, we recorded echolocation calls using Pettersson D240X bat detectors linked to digital recorders at 156 sites. We also sampled nocturnal flying insects at each site using Malaise insect traps. We used negative binomial count regression models to describe bat foraging behavior relative to forest edges, stand types, and prey availability. Although some species showed affinities for certain stand types and prey items, bat activity patterns were most strongly related to forest edges. Edges were used extensively by 6 aerial-hunting bat species, but avoided by Myotis species. Forest edges function similarly to natural forest gaps, by providing foraging opportunities for aerial-hunting bat species. Therefore, the maintenance of forest edges in managed pine landscapes may enhance foraging habitat for aerial-hunting bat species.

Foraging Area Size and Habitat Use by Red Bats (Lasiurus Borealis) in an Intensively Managed Pine Landscape in Mississippi

Abstract Forest managers are increasingly expected to incorporate biodiversity objectives within forest landscapes devoted to timber production. However, reliable data on which to base management recommendations for bats within these systems are extremely limited. Although the red bat (Lasiurus borealis) is a widespread common species in temperate forests of North America, little is known of its ecology within intensively managed pine (Pinus spp.) forests of the southeastern United States. Therefore, we investigated size of foraging areas and habitat use by red bats during summer 2000 and 2001 in an intensively managed pine landscape in east-central Mississippi, USA. We captured bats using four-tier mist nets placed over water and attached radiotransmitters to red bats. Radiotagged red bats (n = 16) used habitat types randomly at the study area and foraging area scale. Mean size of foraging areas and mean maximum distance traveled between diurnal roosts and foraging locations were not different (P < 0.05) among adult male, adult female, juvenile male or juvenile females (n = 18). Most foraging areas contained a reliable source of water and all but one diurnal roost was located within foraging areas. Location of diurnal roosts may dictate location of foraging areas. Open canopy conditions in intensively managed pine stands (young, open canopy stands, thinned stands and riparian hardwood stands) likely provide appropriate foraging habitat for red bats. Landscape context may influence size of foraging areas and commuting distances of red bats. Provision of appropriate aged forest stands for diurnal roosts may be the best management action for red bats within intensively managed pine landscapes.

Habitat use of eastern wild turkeys in central Mississippi

Most past studies of wild turkey (Meleagris gallopavo) habitat use were limited to 1 spatial scale. were of short duration, and had not simultaneously examined habitat use by both sexes. We used compositional analysis to describe habitat use of an castern wild turkey (M. g silvestris) population in central Mississippi at 3 spatial scales (study area, home range, within home range). We conducted the study on the 14,410-ha Tallahala Wildlife Management Area (TWMA), which was composed of hardwood, pine, and pine-hardwood stands of various ages. Overall, turkevs of both sexes preferred pine and hardwood sawtimber most, and poletimber stands least Throughout the vear, females primarily used hardwood sawtimber stands, but males tended to use pine sawtimber. Habital use by females during preincubation may have influenced subsequent nest success. Habitat use at 3 spatial scales was similar and was reflective of the adaptable nature of wild turkeys and the high degree of habitat heterogencity on the study area.

Herbicides and forest biodiversity—what do we know and where do we go from here?

Abstract Use of herbicides to control competing vegetation in young forests can increase wood volume yields by 50–150%. However, increasing use of herbicides in forest management has caused widespread concerns among the public and biologists about direct toxicity to wildlife and indirect effects through habitat alteration. Abundant research has indicated that forest herbicide treatments target biochemical pathways unique to plants, do not persist in the environment, and have few toxic effects when operationally applied. Herbicides affect forest biodiversity by creating short-term declines in plant species diversity, altering vegetative structure, and potentially changing plant successional trajectories. For wildlife species, effects vary but generally are short-term. Despite these findings, public opinion against forest herbicides often has limited or restricted their use, likely due to peoples values associated with forests and a lack of technical knowledge. Future research efforts on relationships between forest herbicides and biodiversity should address landscape and site-specific issues, be based on rigorous experimental design, be relevant to public concerns, include comparisons of herbicide treatments with alternative treatments excluding herbicides, examine use of chemical mixtures, and determine the social, economic, and possible long-term ecological consequences of treatments.

Multi-Scale Roost-Site Selection by Evening Bats on Pine-Dominated Landscapes in Southwest Georgia

Abstract Bats likely incorporate multi-scale criteria when selecting roost sites, which may change across different landscapes. During summers 2002 and 2003, we used radiotelemetry to investigate day-roost selection of evening bats (Nycticeius humeralis) at multiple scales in mature longleaf (Pinus palustris; natural) and intensively managed loblolly pine (P. taeda; managed) landscapes in the Gulf Coastal Plain of Georgia, USA. We used Akaikes Information Criterion (AIC) to evaluate models describing roost-site selection at the tree, plot, stand, and landscape scales. Evening bats on the natural site selected day-roosts based on tree, plot, and landscape characteristics, but bats on the managed site selected day-roosts only at the tree and plot scale. We hypothesize that greater availability of roosting structures (i.e., abundant large trees and snags) throughout the natural site allowed evening bats to select day-roosts that had favorable landscape characteristics (i.e., closer to water and foraging sites), possibly providing benefits from reduced commuting costs. On the managed site, the relatively young age structure of stands resulted in less-abundant roosting structures throughout the landscape, resulting in selection only at the tree and plot scales. Evening bats appeared to select day-roosts that provide energetic benefits when landscape conditions permitted, however, replicated studies are needed to examine the relationship between energetics and roost availability. Land management on pine landscapes of the southeastern United States that promotes large trees, retention of snags, and an open midstory appears to provide abundant roost structures for evening bats. On managed landscapes, roost sites for evening bats may be provided by retention of forked-topped pines in managed stands and by allowing maturation and senescence of trees in set-aside areas, such as streamside management zones, to promote snag and cavity formation.

Habitat selection models for eastern wild turkeys in central Mississippi.

Few quantitative models of habitat use exist for eastern wild turkey (Meleagris gallopavo silvestris). We used logistic regression to build and cross-validate sex- and season-specific multivariate models of habitat selection for wild turkeys in central Mississippi. We examined 4 models: successfully nesting and unsuccessfully nesting females during preincubation, spring males, and summer males. Preincubation females were associated with riparian corridors, perhaps to travel from bottomland areas to upland nesting sites. During preincubation, successfully nesting females were more closely associated with potential nesting habitat than unsuccessfully nesting females. Habitat selection by males during spring corresponded with habitat use of females. During summer, males were nonselective in their habitat choices. Models developed were consistent with and complemented data from previous studies on this area. Our modeling procedure may be useful for other studies of wild turkey habitat selection. We recommend using habitat models in conjunction with habitat use analyses (e.g., use versus availability) to maximize information gained from habitat selection studies. Habitat management for turkeys in a predominantly forested area should include maintenance of riparian corridors and habitat diversity, with a preponderance of mature (>40-yr-old) timber stands, and a 3-4-year burning rotation in mature pine stands.

A meta-analysis of bird and mammal response to short-rotation woody crops

Short‐rotation woody cropping (SRWC) refers to silvicultural systems designed to produce woody biomass using short harvest cycles (1–15 years), intensive silvicultural techniques, high‐yielding varieties, and often coppice regeneration. Recent emphasis on alternatives to fossil fuels has spurred interest in producing SRWC on privately owned and intensively managed forests of North America. We examined potential bird and small mammal response at the stand level to conversion of existing, intensively managed forests to SRWCs using meta‐analysis of existing studies. We found 257 effect sizes for birds (243 effect sizes) and mammals (14 effect sizes) from 8 studies involving Populus spp. plantations. Diversity and abundance of bird guilds were lower on short‐rotation plantations compared with reference woodlands, while abundance of individual bird species was more variable and not consistently higher or lower on SRWC plantations. Shrub‐associated birds were more abundant on SRWC plantations, but forest‐associated and cavity‐nesting birds were less abundant. Effects on birds appeared to decrease with age of the SRWC plantation, but plantation age was also confounded with variation in the type of reference forest used for comparison. Both guilds and species of mammals were less abundant on SRWC plantations. These conclusions are tentative because none of these studies directly compared SRWC plantations to intensively managed forests. Plantations of SRWCs could contribute to overall landscape diversity in forest‐dominated landscapes by providing shrubby habitat structure for nonforest species. However, extensive conversion of mature or intensively managed forests to SRWC would likely decrease overall diversity, especially if they replace habitat types of high conservation value.

Habitat Selection of Female Turkeys in a Managed Pine Landscape in Mississippi

Abstract Intensive pine (Pinus spp.) management is a dominant form of forest management in the southeastern United States. Previous research has shown that managed pine forests provide suitable habitat for eastern wild turkeys (Meleagris gallopavo silvestris), but little research has examined seasonal habitat selection for female wild turkeys from a landscape perspective, particularly within managed pine landscapes. Therefore, we used a long-term (1986–1993) data set to describe seasonal habitat selection by female wild turkeys, using an information-theoretic approach from a landscape perspective, on an intensively managed pine landscape. Habitat use patterns during preincubation and autumn–winter were indicative of female wild turkeys moving between a bottomland hardwood–agricultural field complex during autumn–winter and upland managed pine stands during the remainder of the year. During spring and summer, female wild turkeys used landscapes primarily composed of intensively managed pine, including thinned and burned stands and roadsides. Our results confirm results of short-term, stand-based habitat analyses on our study area. We recommend variable fire return intervals of 3 to 7 years to improve habitat conditions for wild turkeys within intensively managed pine forests. Further research is needed to examine management actions, such as thinning, prescribed fire, and herbicide use, within the context of wild turkey use of intensively managed pine landscapes.

Survival and cause-specific mortality of wild turkey hens in central Mississippi

Most studies of hen survival of eastern wild turkey (Meleagris gallopavo silvestris) have been of short duration ( 0.05). During years of high survival, survival rates of NRA and RA hens did not differ (P > 0.05). Preincubation and fall-winter interval survival rates did not differ within years (P > 0.05). Predation was the primary mortality factor, whereas illegal kill was low. Nesting hens experienced higher predation than NRA hens during years of low (P = 0.009) and medium survival (P < 0.021). Survival cost of reproduction associated with nesting was low but unknown for brood-rearing hens.

Reproductive characteristics of a wild turkey population in central Mississippi

Long-term investigations into wild turkey (Meleagris gallopavo) reproduction are needed to allow for annual fluctuations, illuminate trends not evident from short-term data, and provide data for effective sustainable management of the wild turkey resource. We used 13 years (1984-96) of continuous data to estimate reproductive parameters of a wild turkey population in central Mississippi. Mean rates of reproductive parameters were 72.3% for first-nest initiation rates, 27.9% for first-nest success, 34.8% for renest initiation, and 24.6% for renest success. Median date of incubation ranged from 12 April to 1 May. Juvenile hens did not contribute to reproduction. Hen success declined significantly over time and reflected a decreasing population. Most (51.1%) nest failures were attributed to predation. Poult survival until late July-August was 25.5%. Winter weather did not influence reproductive parameters, and hen experience did not increase nest success. Mean hen success for this population was the lowest reported for any eastern wild turkey (M. g. silvestris) population. Low hen success via lack of productivity from renest attempts, lack of juvenile hen reproduction, and low nest success may have contributed to the population decline. A simplistic population model indicated that, given current reproduction and hen survival, maintaining wild turkeys as a closed population on our area is doubtful.